Gas sampling and management system

ABSTRACT

A gas monitoring and control system including a gas sampling chamber, sampling inlet and outlet valves, a pump and a controller. Sensors are disposed within the interior chamber that sense characteristics of a gas from a gas source and generate representative signals. The sampling inlet and outlet valves i) allow the gas into the gas sampling chamber while operating in a gas sampling state, and ii) allow ambient air into the gas sampling chamber while operating in a purge state. The pump i) causes the gas to flow through the gas sampling chamber while operating in the gas sampling state or ii) causes ambient air to flow through the gas sampling chamber while operating in the purge state. The controller causes the sampling inlet and outlet valves, and the pump to alternate operating in the gas sampling or purge state to selectively expose the sensors to the gas.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 15/046,009, filed Feb. 17, 2016, which claims priority to U.S.Provisional Patent Application No. 62/117,330, filed on Feb. 17, 2015.The entire contents of each application are incorporated herein byreference in their entireties.

BACKGROUND

The present invention generally relates to gas monitoring system and,more particularly, to systems and methods for gas monitoring.

Millions of tons of garbage are deposited into landfills each year. Asthe garbage decomposes, it produces a number of harmful gases. Landfillgas is composed of approximately equal parts (fifty percent (50%)) ofmethane and carbon dioxide, both of which are greenhouse gases. Methanehas a malicious environmental impact nearly twenty (20) times greaterthan that of carbon dioxide over a period of 100 (one hundred) years.According to the Environmental Protection Agency, landfills contributedapproximately eighteen percent (18%) to overall methane emissions in theU.S. in 2012.

To minimize the harmful effects of the landfill gas, landfills extractthe gas and then burn or neutralize it before the gas can escape intothe atmosphere. Landfills utilize hundreds of gas extraction wells toperform this function. In operation, the well system creates a negativepressure in the decomposing trash causing the gas to evacuate from thelandfill. The gas from multiple wells is then collected using a main gasline and transported to a flare where it will be burned off or to anenergy facility where it will be used to generate a form of renewableenergy.

In some situations, such as when oxygen from ambient air mixes into thelandfill gas at the landfill area, the landfill gas's energyeffectiveness is diminished. In these situations, it is more effectiveto regulate the amount of gas evacuating from the landfill area untilthe landfill gas composition becomes more favorable. To regulate gasevacuation, gas wells are fitted with valves. The valves can bepositioned in varying configurations to regulate an amount of landfillgas evacuating to the main gas line. Due to frequent variations in thecomposition of the landfill gas, the gas wells are tuned fastidiouslyand frequently to ensure proper well field operation. Currently, atechnician physically travels to each gas well and measures the landfillgas. The technician then regulates the amount of gas evacuating from thegas well based on the landfill gas measurements. This process is costlyand time consuming, because a technician must travel to each of thehundreds of wells. Also, because the tuning occurs infrequently, gasextraction is less effective.

Additionally, in some situations, gas wells may unexpectedly break orcrack, allowing harmful landfill gas to leak into the environment.Currently, a technician can only detect the gas leak when the technicianis in proximity to the gas well. Because the technician may visit thegas well infrequently, a substantial amount of harmful landfill gas mayleak into the environment before detection occurs, causing environmentalconcerns and producing unpleasant odors for local residents.

SUMMARY

In some embodiments, there is a gas monitoring and control systemincluding a gas sampling chamber having a chamber inlet, a chamberoutlet and an interior chamber; one or more sensors disposed within theinterior chamber, the sensors being operable to sense one or morecharacteristics of a gas from a gas source and generate one or moresensor signals representative of the one or more characteristics of thegas; a sampling inlet valve in operable communication with an outlet ofthe gas source and the chamber inlet; a sampling outlet valve inoperable communication with the chamber outlet and an inlet of the gassource, the sampling inlet valve and the sampling outlet valve areoperable to i) allow the gas from the gas source to enter the gassampling chamber while operating in a gas sampling state, and ii) allowambient air to enter the gas sampling chamber while operating in a purgestate, a pump in operable communication with the sampling inlet valveand the sampling outlet valve, the pump operable to i) cause the gas toflow through the gas sampling chamber while operating in the gassampling state and ii) cause ambient air to flow through the gassampling chamber while operating in the purge state; and/or a controllerin operable communication with the one or more sensors, the samplinginlet valve, the sampling outlet valve and the pump, the controlleroperable to cause the sampling inlet valve, the sampling outlet valveand the pump to alternate operating in the gas sampling state during asampling time period and the purge state during a purge time period toselectively expose the one or more sensors to the gas.

In some embodiments, the sampling time period is less than 2 minutes.

In some embodiments, a time interval between subsequent sampling timeperiods is greater than 1 hour.

In some embodiments, the sampling inlet valve and the sampling outletvalve are operable to facilitate creating a static pressure in the gassampling chamber while operating in a vacuum pressure state; and whereinthe controller is operable to cause the sampling inlet valve and thesampling outlet valve to each operate in the vacuum pressure stateduring a vacuum pressure time period.

In some embodiments, the sampling inlet valve and the sampling outletvalve are operable to isolate the gas sampling chamber from the gaswhile operating in an isolation state; and wherein the controller isoperable to cause the sampling inlet valve and the sampling outlet valveto each operate in the isolation state during an isolation time period.

In some embodiments, the purge time period is less than 2 minutes.

In some embodiments, the controller is operable to cause the samplinginlet valve, the sampling outlet valve and the pump to operate in thegas sampling state in response to receiving a sampling command from anexternal computing device to sample the gas.

In some embodiments, the gas monitoring and control system includes avalve actuator in operable communication with a gas source valve in thegas source; and wherein the controller is in operable communication withthe valve actuator and operable to cause the valve actuator totransition the gas source valve towards an open position or a closedposition when the one or more sensor signals meets valve actuationcriteria to regulate the flow of landfill gas in the wellhead.

In some embodiments, the one or more sensor signals includes a sensorsignal representative of oxygen concentration of the gas.

In some embodiments, the one or more sensor signals meets valveactuation criteria when the one or more sensor signals exceeds aconcentration threshold; and in response, the controller causes thevalve actuator motor to transition the gas source valve towards theclosed position.

In some embodiments, the one or more sensor signals meets valveactuation criteria when the one or more sensor signals falls below aconcentration threshold; and in response, the controller causes thevalve actuator motor to transition the gas source valve towards the openposition.

In some embodiments, the one or more sensor signals meets valveactuation criteria when a positive rate of change of the one or moresensor signals exceeds a concentration change rate threshold; and inresponse, the controller causes the valve actuator motor to transitionthe gas source valve towards the closed position.

In some embodiments, the one or more sensor signals meets valveactuation criteria when a negative rate of change of the one or moresensor signals exceeds a concentration change rate threshold; and inresponse, the controller causes the valve actuator motor to transitionthe gas source valve towards an open position.

In some embodiments, the controller is operable to cause the valveactuator motor to transition the gas source valve towards the openposition or the closed position when a second set of one or more sensorsignals sampled at a second gas source meets valve actuation criteria.

In some embodiments, the second set of one or more sensor signals meetsvalve actuation criteria when the second set of one or more sensorsignals is less than the one or more sensor signals; and in response,the controller is operable to cause the valve actuator motor totransition the gas source valve towards the open position.

In some embodiments, the second set of one or more sensor signals meetsvalve actuation criteria when the second set of one or more sensorsignals is greater than the one or more sensor signals; and in response,the controller is operable to cause the valve actuator motor totransition the gas source valve towards the closed position.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofembodiments of the invention, will be better understood when read inconjunction with the appended drawings of an exemplary embodiment. Itshould be understood, however, that the invention is not limited to theprecise arrangements and instrumentalities shown.

In the drawings:

FIG. 1 is a side view of a gas wellhead and a system configured tomonitor gas from a wellhead and control gas traveling from a landfillarea to a main gas line, according to at least one embodiment of theinvention.

FIG. 2 is a schematic diagram illustrating exemplary components of thegas monitoring and control system, according to at least one embodimentof the invention.

FIG. 3A shows a perspective view of some of the exemplary components ofthe gas monitoring and control system for sampling landfill gasaccording to at least one embodiment of the invention.

FIG. 3B is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing a gassampling phase, according to at least one embodiment of the invention.

FIG. 3C is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing a vacuummeasurement phase, according to at least one embodiment of theinvention.

FIG. 3D is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing a purgephase, according to at least one embodiment of the invention.

FIG. 3E is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing anisolation phase, according to at least one embodiment of the invention.

FIG. 4 shows an exploded perspective view of some of the exemplarycomponents of the gas monitoring and control system for regulatinglandfill gas evacuation according to at least one embodiment of theinvention.

FIG. 5 is a diagram of the controller shown in FIG. 2, according to atleast one embodiment of the invention.

FIG. 6 shows a perspective view of the housing of system according to atleast one embodiment of the invention.

DETAILED DESCRIPTION

Embodiments of the invention allow for efficient monitoring and tuningof a wellhead. By providing users with real-time, instantaneousmonitoring and control capabilities, embodiments of the invention candetect gas leaks quickly and efficiently, thereby significantly minimizethe amount of gas lost by extraction/transport facilities. As a result,embodiments of the invention provide economic and industrial benefits byoptimizing production of renewable energy and minimizing environmentalrisk and enhancing safety for those who maintain, monitor, assess andcheck the wellheads.

Referring to the drawings in detail, wherein like reference numeralsindicate like elements throughout, there is shown in FIGS. 1-6, a systemmonitoring and controlling gas evacuation, generally designated, inaccordance with an exemplary embodiment of the present invention.

FIG. 1 is a side view of a gas wellhead 10 and a system 100 configuredto monitor gas from the wellhead 10 and control gas travelling from alandfill area to a main gas line, according to at least one embodimentof the invention. In FIG. 1, the wellhead 10 is connected to a landfillarea 11 containing landfill waste. Over time, the landfill wasteproduces landfill gas. This landfill gas travels from the landfill area11, through the wellhead 10, to the main gas line 12. Then, the gas maybe transported to a flare for incineration or an energy facility forgenerating renewable energy.

In some embodiments, the system 100 includes a gas monitoring andcontrol system 102 (illustrated, for example, in FIG. 3A) disposed in ahousing 101 of system 100. The gas monitoring and control system 102 iscouplable to the wellhead 10. The gas monitoring and control system 102is configured to receive the landfill gas from the wellhead 10, monitorthe characteristics of the landfill gas and perform further actionsbased on the monitored characteristics. For example, in someembodiments, the gas monitoring and control system 102 regulates theamount of landfill gas evacuating from the landfill area 11. Examplesfor regulating landfill gas evacuation, such as repositioning a wellheadvalve 430 (e.g., a ball valve as illustrated in FIG. 1) of wellhead 10to open or close an aperture in the wellhead 10, are described in moredetail below. Alternatively, in some embodiments, the gas monitoring andcontrol system 102 communicates landfill gas data to an externalcomputing device (e.g., a central control system), external to system100, to alert a technician to problems with the wellhead 10 or main gasline 12. In some embodiments, the gas monitoring and control system 102receives commands from the external computing device causing the gasmonitoring and control system 102 to regulate the amount of landfill gasevacuating from the landfill area 11. As a result of continuousmonitoring of the wellhead 10, problems with the landfill gas orwellhead 10 can be detected quickly, allowing for quick regulation oflandfill gas transmitted to the main gas line 12 without the need for atechnician to manually inspect the wellhead 10.

Gas Monitoring

FIG. 2 is a schematic diagram illustrating exemplary components of thegas monitoring and control system 102, according to at least oneembodiment of the invention.

In some embodiments, the gas monitoring and control system 102 includesa gas sampling chamber 201. Gas sampling chamber 201 may be configuredas an internal chamber located within the wellhead 10. Gas samplingchamber 201 may be configured as a by-pass chamber within a wellhead 10.Gas sampling chamber 201 may be configured to isolate electricalcomponents, such as pumps, controllers and power sources (described inmore detail throughout) from the landfill gas.

The gas sampling chamber 201 includes an inlet port 202 configured toreceive gas from a source such as the wellhead 10 and an outlet port 203configured to transport landfill gas to an outlet such as back to thewellhead 10. The gas sampling chamber 201 may be of a fixed volume andmay be configured to house one or more sensors (e.g., sensors 204, 206,208) to measure characteristics of the landfill gas in the wellhead 10.In some embodiments, the gas sampling chamber 201 encloses the one ormore sensors in an airtight enclosure to improve sensor measurementaccuracy. The sensors may include one or more of an oxygen sensor, amethane sensor, a carbon dioxide sensor, a temperature sensor, pressuresensor, a humidity sensor and a flow rate sensor.

In some embodiments, one of the sensors that may be positioned in thegas sampling chamber 201 is an oxygen sensor 204. The oxygen sensor 204is an electronic device that measures the concentration of oxygen in thelandfill gas. In some embodiments, the oxygen sensor 204 is an opticaloxygen sensor. In some embodiments, the oxygen sensor 204 is the LuminOxmanufactured by SST Sensing Ltd.

In some embodiments, the gas monitoring and control system 102 includesa methane sensor that may be positioned in the gas sampling chamber 201.The methane sensor is an electronic device that measures theconcentration of methane in the landfill gas. In some embodiments, oneof the sensors in the gas monitoring and control system 102 is a carbondioxide sensor that may be positioned in the gas sampling chamber 201.The carbon dioxide sensor is an electronic device that measures theconcentration of carbon dioxide in the landfill gas. In someembodiments, and as shown in FIG. 2, one of the sensors in the gasmonitoring and control system 102 is a dual methane/CO₂ sensor 206positioned in the gas sampling chamber 201. In some embodiments, thedual methane/CO₂ sensor 206 is the SIL1 manufactured by Dynament.

In some embodiments, one or more sensors positioned in the gas samplingchamber 201 may degrade more quickly when exposed to moisture(condensate). To mitigate exposure to condensation that may accumulateat the bottom of gas sampling chamber 201, in some embodiments, the oneor more sensors are positioned at a top side (relative to gravity) ofthe gas sampling chamber 201. In some embodiments, the gas monitoringand control system 102 includes a humidity sensor 208 that may bepositioned in the gas sampling chamber 201. The humidity sensor 208 isan electronic device that measures an amount of humidity in the landfillgas. The humidity sensor 208 is used to detect condensate build up insampling chamber and lines. For example, if a humidity sensor 208detects humidity in the gas sampling chamber 201 that meets humiditycriteria (e.g., measured humidity exceeds a humidity threshold), thecontroller 210 may cause the gas sampling chamber 201 to be purged withambient air to reduce humidity and protect the sensors. In someembodiments, the humidity sensor 208 is the HIH-5030 manufactured byHONEYWELL®.

In some embodiments, other examples of sensors include sensors ordetectors for determining the presence/amounts of methane, carbonmonoxide, chlorine, cyanide, hydrogen, hydrogen sulfide, nitric oxides,nitrogen, sulfur oxides, overall gas composition, differential pressurein the wellhead, wellhead gas and ambient air temperature, appliedvacuum pressure of wellhead, and gas flow.

The gas monitoring and control system 102 may also include a controller210 configured to receive one or more sensor signals from the one ormore sensors, process the sensor signals, and transmit the sensorsignals to an external computing device. Based on the sensor signalsrepresentative of landfill gas composition, the controller 210 mayperform further actions, such as generating alerts for technicians oractuating a wellhead valve to open or close the wellhead 10. Theseactions are described in more detail throughout.

Gas Sampling Routine

Prolonging exposure of the sensors to a harsh surrounding landfill gasenvironment of can cause the sensors to wear quickly over time. Tomitigate sensor wear and degradation, the gas monitoring and controlsystem 102 is configured to selectively expose the sensors to thelandfill gas during a pre-selected sampling interval or a samplinginterval that is variable based on landfill conditions. Exposure tolandfill gas environment on a less frequent or intermitted basis mayextend the life of the landfill gas sensors.

FIG. 3A shows a perspective view of some of the exemplary components ofthe gas monitoring and control system 102 for sampling landfill gasaccording to at least one embodiment of the invention.

In some embodiments, the gas monitoring and control system 102 includesa housing inlet port 240 that allows landfill gas from the wellhead 10to enter the housing 101. The gas monitoring and control system 102 alsoincludes a housing outlet port 242 that allows landfill gas in thehousing to enter the wellhead 10.

In some embodiments, the gas monitoring and control system 102 includesan inlet sampling valve 220 and an outlet sampling valve 230 configuredto selectively allow the landfill gas to flow into the gas samplingchamber 201, exposing the sensors to the landfill gas. The inletsampling valve 220 connects the housing inlet port 240 to the inlet port202 of gas sampling chamber 201. The outlet sampling valve 230 connectsthe outlet port 203 (not shown in FIG. 3) of gas sampling chamber 201 tothe housing outlet port 242.

The inlet sampling valve 220 includes a landfill gas inlet port 222that, when open, connects the housing inlet port 240 to the gas samplingchamber 201 to allow landfill gas to enter the gas sampling chamber 201.In some embodiments, the inlet sampling valve 220 is a three-way valvethat includes an ambient air inlet port 224. When the ambient air inletport 224 is open, the inlet sampling valve 220 prevents landfill gasfrom entering the gas sampling chamber 201. Instead, the inlet samplingvalve 220 allows ambient air to enter the gas sampling chamber 201.

The outlet sampling valve 230 includes an inlet port 232 that, whenopen, connects the outlet port 203 of the gas sampling chamber 201 (notshown) to the housing outlet port 242 and allows landfill gas or ambientair to evacuate into the wellhead 10.

The sampling valves 220, 230 are configured to selectively andtemporarily allow landfill gas to enter the gas sampling chamber 201 sothat sensors positioned in the gas sampling chamber 201 can measure thecomposition of the landfill gas while minimizing the amount of time thesensors are exposed to the landfill gas. For example, after exposing theone or more sensors in the gas sampling chamber 201 to landfill gas, thesampling valves are configured to allow ambient air to enter the gassampling chamber 201 to purge the landfill gas from the gas samplingchamber 201.

In some embodiments, the inlet sampling valve 220 and outlet samplingvalve 230 each operate in different operating states. When the inletsampling valve 220 is a three-way valve and is in a first operatingstate, the inlet sampling valve 220 opens the landfill gas inlet port222 and connects the housing inlet port 240 to the gas sampling chamber201, thereby allowing landfill gas to flow into the gas sampling chamber201. When the inlet sampling valve 220 is in a second operating state,the inlet sampling valve opens the ambient air inlet port 224, therebyallowing ambient air to flow into the gas sampling chamber 201. When theoutlet sampling valve 230 is in a first operating state, the inlet port232 is open, thereby allowing landfill gas or ambient air to evacuate tothe gas sampling chamber 201. When the outlet sampling valve is in asecond operating state, the inlet port 232 is closed, thereby preventinglandfill gas or ambient air to evacuate to the gas sampling chamber 201.

In some embodiments, the controller 210 is connected to the inletsampling valve 220 and the outlet sampling valve 230. In theseembodiments, the controller 210 causes the sampling valves 220, 230 tooperate in a selected operating state. For example, in some embodiments,the sampling valves are solenoid valves. In these embodiments, thecontroller 210 transmits an electrical control signal (e.g., electriccurrent) to cause each of the sampling valves to operate in a selectedoperating state, either by maintaining a sampling valve in the currentoperating state or by causing a sampling valve to transition to theoperating state. In some embodiments, if the valve receives anelectrical control signal from the controller 210 that meets operatingstate criteria (e.g., electrical current exceeds a selected threshold),the valve operates in a first operating state. In these embodiments, ifthe valve receives electrical power from the controller 210 that doesnot meet the operating state criteria, the valve operates in a secondoperating state.

In some embodiments, the gas monitoring and control system 102 includesa gas sampling pump 250. The gas sampling pump 250 is configured to pumplandfill gas or ambient air into and through the gas sampling chamber201 after the gas sampling pump 250 receives an electrical controlsignal (e.g., electrical power) from the controller 210. As a result,the gas sampling pump 250, in conjunction with the sampling valves,causes landfill gas to selectively enter the gas sampling chamber 201and causes selective purging of the landfill gas from the gas samplingchamber 201 based on electrical control signals received from thecontroller 210.

Using the controller 210, the gas monitoring and control system 102 canoperate in, and alternate between, multiple operating phases to measurecharacteristics of the landfill gas while also limiting the one or moresensors in the gas sampling chamber 201 to landfill gas. Examples ofthese operating phases include gas sampling phase, vacuum measurementphase, purge phase and sensor isolation phase.

FIG. 3B is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing a gassampling phase, according to at least one embodiment of the invention.In the gas sampling phase, the controller 210 causes the inlet samplingvalve 220, the outlet sampling valve 230 and the gas sampling pump 250to operate in a gas sampling state. In these embodiments, the controller210 causes the landfill gas inlet port 222 of the inlet sampling valve222 and the inlet port 232 of the outlet sampling valve 230 to open,allowing landfill gas to flow through the gas sampling chamber 201. Insome embodiments, the controller 210 also causes the gas sampling pump250 to pump landfill gas (i.e., turn on) into and through the gassampling chamber 201. In some alternative embodiments, negative pressurecreated in the wellhead 10 may cause landfill gas to flow into andthrough the gas sampling chamber 201, without the use of gas samplingpump 250. During the gas sampling phase, the one or more sensorspositioned in the gas sampling chamber 201 measure the composition ofthe landfill gas. The sensor output signals are subsequently transmittedto the controller 210 for further processing.

FIG. 3C is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing a vacuummeasurement phase, according to at least one embodiment of theinvention. In the vacuum measurement phase, the controller 210 causesthe inlet sampling valve 220, the outlet sampling valve 230 and the gassampling pump 250 to operate in a vacuum measurement state. In theseembodiments, the controller 210 causes the landfill gas inlet port 222of the inlet sampling valve 220 to open and causes the inlet port 232 ofthe outlet sampling valve 230 to close. Also, the controller 210 causesthe gas sampling pump 250 to cease pumping (i.e., turn off). As aresult, when there is a negative pressure presented inside the wellhead10, a negative pressure in the gas sampling chamber 201 is also created.A static pressure sensor, connected to the gas sampling chamber 201 viaa vacuum tube, measures vacuum pressure of the wellhead 10. The sensoroutput signals are subsequently transmitted to the controller 210 forfurther processing.

FIG. 3D is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing a purgephase, according to at least one embodiment of the invention. In thepurge phase, the controller 210 causes the inlet sampling valve 220, theoutlet sampling valve 230 and the gas sampling pump 250 to operate in apurge state. In these embodiments, the controller 210 causes the ambientair inlet port 224 of the inlet sampling valve 220 to open and causesthe inlet port 232 of the outlet sampling valve 230 to close. Thecontroller 210 also causes the gas sampling pump 250 to pump ambient airthrough the gas sampling chamber 201. As a result, ambient air entersthe gas sampling chamber 201, thereby purging the landfill gas from thegas sampling chamber 201.

FIG. 3E is a process flow diagram illustrating exemplary components ofthe gas monitoring and control system of FIG. 3A implementing anisolation phase, according to at least one embodiment of the invention.In the isolation phase, the controller 210 causes the inlet samplingvalve 220, the outlet sampling valve 230 and the gas sampling pump 250to operate in an isolation state. In these embodiments, the controller210 causes the ambient air inlet port 224 of the inlet sampling valve220 to open and causes the inlet port 232 of the outlet sampling valve230 to close. Also, the controller 210 causes the gas sampling pump 250to cease pumping. As a result, the sensors in the gas sampling chamber201 are isolated from the corrosive landfill gas to minimize the sensorsexposure to the landfill gas and minimizing sensor degradation.

In some embodiments, the controller 210 receives one or more gassampling commands to sample the landfill gas from an external computingdevice. In response, the controller 210 implements the gas samplingphase and/or vacuum measurement phase. Upon completion, the controller210 implements the purge phase and the isolation phase. As a result, atechnician can manually control sampling of the landfill gas at thewellhead 10 from an external computing device at a remote location.

In some embodiments, the sampling phase has a sampling time period ofless than 10 seconds, less than 30 seconds, less than 1 minute, lessthan 5 minutes, less than 10 minutes, less than 30 minutes, less than 1hour, less than 12 hours, or less than 24 hours.

In some embodiments, the purge phase has a purge time period of lessthan 10 seconds, less than 30 seconds, less than 1 minute, less than 5minutes, less than 10 minutes, less than 30 minutes, less than 1 hour,less than 12 hours, or less than 24 hours.

In some embodiments, the isolation phase has an isolation time period ofless than 10 seconds, less than 30 seconds, less than 1 minute, lessthan 5 minutes, less than 10 minutes, less than 30 minutes, less than 1hour, less than 12 hours, or less than 24 hours.

In some embodiments, the vacuum measurement phase has a vacuummeasurement time period of less than 10 seconds, less than 30 seconds,less than 1 minute, less than 5 minutes, less than 10 minutes, less than30 minutes, less than 1 hour, less than 12 hours, or less than 24 hours.

In some embodiments, each of the gas sampling phase, the purge phase,the isolation phase and/or the vacuum measurement phase operate innon-overlapping time periods.

In some embodiments, the sampling time interval between successivesampling time periods is greater than 5 seconds, greater than 10seconds, greater than 30 seconds, greater than 1 minute, greater than 5minutes, greater than 10 minutes, greater than 30 minutes, greater than1 hour, greater than 12 hours, greater than 24 hours, greater than 1week, or greater than 1 month.

In some embodiments, the purge time interval between successive purgetime periods is greater than 5 seconds, greater than 10 seconds, greaterthan 30 seconds, greater than 1 minute, greater than 5 minutes, greaterthan 10 minutes, greater than 30 minutes, greater than 1 hour, greaterthan 12 hours, greater than 24 hours, greater than 1 week, or greaterthan 1 month.

In some embodiments, the vacuum measurement time interval betweensuccessive vacuum measurement time periods is greater than 5 seconds,greater than 10 seconds, greater than 30 seconds, greater than 1 minute,greater than 5 minutes, greater than 10 minutes, greater than 30minutes, greater than 1 hour, greater than 12 hours, greater than 24hours, greater than 1 week, or greater than 1 month.

In some embodiments, the isolation time interval between successiveisolation time periods is greater than 5 seconds, greater than 10seconds, greater than 30 seconds, greater than 1 minute, greater than 5minutes, greater than 10 minutes, greater than 30 minutes, greater than1 hour, greater than 12 hours, greater than 24 hours, greater than 1week, or greater than 1 month.

Valve Actuation

In certain situations, it may be favorable to regulate the amount oflandfill gas expelled from the landfill area 11 based on the compositionof landfill gas to optimize gas collection. For example, higher levelsof methane in the landfill gas improves the recovery of energy throughregeneration techniques, because higher levels of methane produce moreenergy when burned. In these situations, it may be favorable to increasethe amount of landfill gas evacuating from the wellhead 10. In contrast,higher levels of oxygen in the landfill gas may indicate that the gaswell is extracting more gas than is being produced by garbagedecomposition. In these situations, it may be favorable to decrease theamount of landfill gas evacuating from the wellhead 10.

FIG. 4 shows an exploded perspective view of some of the exemplarycomponents of the gas monitoring and control system 102 for regulatinglandfill gas evacuation according to at least one embodiment of theinvention. As shown, the gas monitoring and control system 102 includesa position sensor 402, a position sensor coupling 404, a limit triggercam 406, a closed limit switch 408, an open limit switch 410, anactuator carriage 412, a gearbox 414, an enclosure mounting 416, a valveactuator motor 418, valve actuator shaft 420 and controller 210.

In some embodiments, the gas monitoring and control system 102 adjusts aposition of a wellhead valve 430 in the wellhead 10 towards an openposition or a closed position when sensor data collected by the sensorsin the gas sampling chamber 201 to regulate landfill gas evacuation. Forillustrative purposes, FIG. 4 shows a cutout of the wellhead valve 430and the wellhead 10.

In some embodiments, the wellhead valve 430 is coupled to one end of thevalve actuator shaft 420. The valve actuator motor 418 is also coupledto the valve actuator shaft 420 in a configuration that allows the valveactuator motor 418 to rotate the valve actuator shaft 420 using gearbox414. In some embodiments, the valve actuator motor 418 causes valveactuator shaft 420 to rotate axially in response to receiving anelectrical control signal from the controller 210. As the valve actuatorshaft 420 rotates, the wellhead valve 430 rotates as well, causing awellhead aperture to either increase or decrease in size.

In some embodiments, the controller 210 is configured to cause thewellhead valve 430 to rotate to an open position and a closed position.When the controller 210 causes the wellhead valve 430 to rotate towardan open position, an aperture size in the wellhead 10 increases, therebyincreasing the amount of landfill gas evacuating to the main gas line12. In the open position, the wellhead valve 430 substantially allowsthe landfill gas to evacuate through the wellhead 10. When thecontroller 210 causes the wellhead valve 430 to rotate toward a closedposition, an aperture size in the wellhead 10 decreases, therebydecreasing the amount of landfill gas evacuating to the main gas line12. In the closed position, the wellhead valve 430 substantiallyprevents the landfill gas from evacuating through the wellhead 10.

In some embodiments, a closed limit switch 408 and an open limit switch410 are positioned on an actuator carriage 412 to prevent over-rotationof the wellhead valve 430. A limit trigger cam 406 is coupled to one endof the valve actuator shaft 420. As the valve actuator shaft 420rotates, the limit trigger cam also rotates. When the valve actuatorshaft 420 rotates to a closed position the limit trigger cam 406contacts the closed limit switch 408. When the valve actuator shaft 420rotates to an open position the limit trigger cam 406 contacts the openlimit switch 410. When the limit trigger cam 406 contacts one of thelimit switches 408, 410, the contacted limit switch transmits a contactalert to the controller 210. In response, the controller 210 ceasesrotation of the wellhead valve 430.

In some embodiments, the controller 210 is configured to cause thewellhead valve 430 to rotate to one of a plurality of positions betweenthe open position and the closed position. In these embodiments, aposition sensor 402 (e.g., potentiometer) is positioned on an end of thewellhead valve shaft for valve position sensing. The position sensor 402is coupled to the valve actuator shaft 420 via a position sensorcoupling 404.

In some embodiments, controller 210 causes the wellhead valve 430 (e.g.,via actuator shaft 420 and valve actuator motor 418) to rotate toward anopen or closed position based on valve actuation criteria. Examples ofvalve actuation criteria may include i) one or more sensor signalsexceeding or falling below a characteristic threshold for one or morecharacteristics (e.g., oxygen, methane, carbon dioxide) of the landfillgas; ii) a positive or negative rate of change of one or more sensorsignals exceeding a change rate threshold; and iii) one or more sensorsignals from a second wellhead separate from wellhead 10 being less thanor greater than the one or more sensor signals from wellhead 10.

In some embodiments, an amount of a characteristic (e.g., oxygen) in thelandfill gas is inversely proportional to the preferred amount oflandfill gas evacuating from the wellhead 10. In these embodiments, if asensor signal representative of an amount of a characteristic of thelandfill gas exceeds a concentration threshold (e.g., 3% for oxygen),then controller 210 causes the wellhead valve 430 to rotate toward aclosed position. In these embodiments, if a sensor signal representativeof an amount of a characteristic of the landfill gas falls below aselect threshold (e.g., 1% for oxygen), then controller 210 causes thewellhead valve 430 to rotate toward an open position. Conversely, if anamount of a characteristic (e.g., methane, carbon dioxide) in thelandfill gas is proportional to the preferred amount of landfill gasevacuating from the wellhead 10, the controller 210 causes the wellheadvalve 430 to rotate in the opposite direction.

In some embodiments, the rate of change of one or more characteristics(e.g., oxygen) of the landfill gas is inversely proportional to thepreferred amount of landfill gas evacuating from the wellhead 10. Inthese embodiments, if a positive rate of change measured from multiplesensor signals over time exceeds a change rate threshold, thencontroller 210 causes the wellhead valve 430 to rotate towards a closedposition. Also, in these embodiments, if a negative rate of changemeasured from multiple sensor signals over time falls below a changerate threshold, then controller 210 causes the wellhead valve 430 torotate towards an open position. Conversely, if the rate of change ofone or more characteristics of the landfill gas is proportional to thepreferred amount of landfill gas evacuating from the wellhead 10, thecontroller 210 causes the wellhead valve 430 to rotate in the oppositedirection.

By sampling the landfill gas at a substantially smaller time intervalthan a technician can inspect the wellhead 10, the gas monitoring andcontrol system 102 can adjust the wellhead valve 430 more often, therebyallowing the landfill gas to evacuate from the wellhead 10 when thelandfill gas has favorable characteristics.

In some embodiments, the wellhead 10 is one of a plurality of wellheadsconnected to the main gas line 12. In some situations, it may bebeneficial to regulate landfill gas flow from the wellhead 10 based onlandfill gas characteristics from another wellhead 10. For example, if arenewable energy facility can only receive a fixed amount of landfillgas over a certain time period (e.g., 1000 cu. ft./minute) and thewellhead 10 along with a second wellhead supply more landfill gas (e.g.,2000 cu. ft./minute) than the fixed amount, the excess landfill gas maybe wasted for renewable energy purposes. To address this problem, insome embodiments, controller 210 may be configured to receive data(e.g., sensor data or commands from a remote computing device)representative of landfill gas at a second wellhead and cause thewellhead valve 430 to rotate towards either an open position or closedposition based on the sensor data representative of landfill gas at thewellhead 10 as well as sensor data representative of landfill gas at thesecond wellhead separate from the wellhead 10. For example, if the gascharacteristics of the landfill gas from the second wellhead is morefavorable than the gas characteristics of the landfill gas from thewellhead 10 (e.g., has a higher level of methane concentration than thelandfill gas in the wellhead 10), controller 210 may cause the wellheadvalve 430 to rotate towards a closed position while a controller at thesecond wellhead may cause the wellhead valve of the second wellhead torotate towards an open position, or vice versa. Alternatively, if thegas characteristics of the landfill gas from the wellhead 10 is morefavorable than the gas characteristics of the landfill gas from thesecond wellhead (e.g., has a higher level of methane concentration thanthe landfill gas in the second wellhead), controller 210 may cause thewellhead valve 430 to rotate towards an open position while a controllerat the second wellhead may cause the wellhead valve of the secondwellhead to rotate towards a closed position, or vice versa. As aresult, the renewable energy facility receives landfill gas having amore favorable composition as a combination of the landfill gas from thewellhead 10 and the landfill gas from the second wellhead.

In some embodiments, the plurality of wellheads is greater than 2;greater than 3; greater than 4; greater than 5; greater than 10; greaterthan 20; greater than 50; greater than 100; greater than 200; or greaterthan 500. As the number of wellheads increases, continuous and automaticmonitoring using technicians that physically visit each wellhead becomestechnically challenging and cost-prohibitive. As a result, a singletechnician or computing device can monitor landfill gas from a pluralityof wellheads and adjust the respective wellhead valves of the wellheadsin real-time to optimize the landfill gas composition in the main gasline 12.

Safety/Diagnostic

In some embodiments, the controller 210 is configured to detectdangerous or undesirable operating conditions within the housing 101.Examples of dangerous or undesirable operating conditions include, butare not limited to: component failures, high ambient methane levels, andrequired maintenance detection. In response to detecting a dangerous orundesirable operating condition, the controller 210 transmits an alertto a user at a remote computing device.

In some embodiments, a methane sensor is positioned within the housing101 but outside of the gas sampling chamber 201 to measure ambientmethane levels. The sensor data of the methane sensor is transmitted tothe controller 210. The controller 210 is configured to determinewhether levels of ambient methane meet ambient methane safety criteria(e.g., exceeds a select ambient methane threshold). When the level ofambient methane meets the ambient methane safety criteria, controller210 may cease actuation of the wellhead valve 430, and/or generate andtransmit an alert to a user at a remote computing device.

In some embodiments, the controller 210 includes current feedbacksensing of the valve actuator motor 418, sampling valves 420, 430 and/orgas sampling pump 250. Current feedback sensing of the motor 418,sampling valves 420, 430 and pump 250 can be used to detect solenoidvalve failures, condensate build up within the pump or gas samplinglines, or pump or motor failure, among others. When the current feedbacksensing meets the current feedback safety criteria (e.g., exceeds aselect current feedback threshold), controller 210 may cease actuationof the actuator motor 418, sampling valves 420, 430 and/or gas samplingpump 250, and/or generate and transmit an alert to a user at a remotecomputing device.

In some embodiments, the controller 210 is configured to generate andtransmit an alert if a sensor signal (e.g., from sensors 204, 206, 208)meets sensor signal alert criteria (e.g., exceeds a select threshold).For example, in some embodiments, the controller 210 may generate analert if the oxygen concentration, measured by the oxygen sensor 204exceeds 5% of the total composition of the landfill gas. In someembodiments, the controller 210 may generate an alert if the methane orcarbon dioxide concentration, measured by the methane/carbon dioxidesensor 206 exceeds 50% of the total composition of the landfill gas. Insome embodiments, the controller 210 may generate an alert if thehumidity, measured by the humidity sensor 208 exceeds 90% relativehumidity. When a sensor signal meets sensor signal alert criteria, itmay indicate that there is a problem with the wellhead 10 requiringphysical inspection by a technician.

General Computer/Communications

FIG. 5 is a diagram of controller 210 shown in FIG. 2, according to atleast one embodiment of the invention.

Controller 210 includes a processor 512. Processor 512 may be any typeof processor, including but not limited to a special purpose or ageneral-purpose digital signal processor. Processor 512 may be connectedto a communication infrastructure 511 (e.g. a data bus or computernetwork) either via a wired connection or a wireless connection.Communication infrastructure 511 carries signals and may be implementedusing wire or cable, fiber optics, a phone line, a wireless link, acellular phone link, a radio frequency link, or any other suitablecommunication channel, including a combination of the foregoingexemplary channels.

Controller 210 includes memory 513. Memory 513 may include at least oneof: random access memory (RAM), a hard disk drive and a removablestorage drive, such as a floppy disk drive, a magnetic tape drive, or anoptical disk drive. The removable storage drive reads from and/or writesto a removable storage unit. The removable storage unit can be a floppydisk, a magnetic tape, an optical disk, which is read by and written toa removable storage drive.

In alternative implementations, memory 513 may include other similarmeans for allowing computer programs or other instructions to be loadedinto controller 210. Examples may include a removable storage unit andan interface. Examples may include a removable memory chip (such as anEPROM, or PROM, or flash memory) and associated socket, and otherremovable storage units and interfaces which allow data to betransferred from removable storage unit to controller 210.Alternatively, the program may be executed and/or the data accessed fromthe removable storage unit, using the processor 512 of the controller210.

Controller 210 includes a user interface 514. User interface 514 may bea program that controls a display (not shown) of controller 210, onwhich the output of the processes described herein can be displayed.User interface 514 may include one or more peripheral user interfacecomponents, such as a keyboard or a mouse. The end user may use theperipheral user interface components to interact with controller 210.User interface 514 may receive user inputs, such as mouse inputs orkeyboard inputs from the mouse or keyboard user interface components.

Controller 210 may also include a communication interface 515.Communication interface 515 allows data to be transferred betweencontroller 210 and an external device 520 (e.g., central controlsystem). Examples of communication interface 515 may include a modem, anetwork interface (such as an Ethernet card), and a communication port,by way of example. Data transferred via communication interface 515 arein the form of signals, which may be electronic, electromagnetic,optical, or other signals capable of being received by communicationinterface 515. These signals are provided to communication interface 515via a communication infrastructure 511.

In some embodiments, the external device 520 may be outside of atransmission range of the communication interface 515. In theseembodiments, if a second gas monitoring and control system positioned atanother wellhead is inside the transmission range of the communicationinterface 515, the communication interface 515 may communicate with theexternal device via the second gas monitoring and control system via amesh network using Digimesh or ZigBee protocols.

In some embodiments, the controller 210 receives power from a fixedpower source (e.g., a battery). In some embodiments, the controller 210receives power from a regenerative power source (e.g., solar panels). Insome embodiments, one or more solar panels are positioned on the housing101 to provide direct power to the controller 210 or recharge the fixedpower source.

FIG. 6 shows a perspective view of the housing 101 of the system 100according to at least one embodiment of the invention. In FIG. 6, aplurality of solar panels 601 a, 601 b, 601 c, 601 d, 601 e, may bepositioned on the housing 101. In some embodiments, the plurality ofsolar panels may be positioned omni-directionally to maximize exposureto the sun and thereby maximize power generation via solar power.

Alternative Embodiments

It is contemplated that embodiments of the invention described hereinfor landfill gas extraction are exemplary, and that embodiments of theinvention extend beyond use solely in the landfill gas extraction fieldto any technology or system that involves detection of flow, emission orcomposition of gas or liquid. This includes early detection andmitigation of gas transport pipes leaks, both in municipal andindustrial settings. Embodiments of the invention can facilitate largenatural gas pipeline leak detection, or within a landfill's internal gastransport system. Embodiments of the invention may be used for urbanplanning by monitoring old or damaged gas lines throughout cities anddetecting aberrational migratory gases. Embodiments of the invention canalso be used for natural gas drill sites such as those in the MarcellusShale to detect migratory gases, control flow valves, or use lowerExplosive or flammable Limit sensors to warn workers of an unsafeenvironment.

Embodiments of the invention may be used in agricultural applications.In these embodiments, sensors, such as soil moisture sensors, may assesscrop health and respond to such feedback, by, for example, controlling awater flow valve for irrigation. Thus, the foregoing examples anddescription of the embodiments of the invention described herein shouldbe interpreted as illustrating, rather than as limiting, the presentinvention as defined herein. All variations and combinations of thefeatures above are intended to be within the scope of this applicationand the following claims.

In at least one embodiment, there is included one or more computershaving one or more processors and memory (e.g., one or more nonvolatilestorage devices). In some embodiments, memory or computer readablestorage medium of memory stores programs, modules and data structures,or a subset thereof for a processor to control and run the varioussystems and methods disclosed herein. In one embodiment, anon-transitory computer readable storage medium having stored thereoncomputer-executable instructions which, when executed by a processor,perform one or more of the methods disclosed herein.

It will be appreciated by those skilled in the art that changes could bemade to the exemplary embodiments shown and described above withoutdeparting from the broad inventive concept thereof. It is understood,therefore, that this invention is not limited to the exemplaryembodiments shown and described, but it is intended to covermodifications within the spirit and scope of the present invention asdefined by the claims. For example, specific features of the exemplaryembodiments may or may not be part of the claimed invention and featuresof the disclosed embodiments may be combined. Unless specifically setforth herein, the terms “a”, “an” and “the” are not limited to oneelement but instead should be read as meaning “at least one”.

It is to be understood that at least some of the figures anddescriptions of the invention have been simplified to focus on elementsthat are relevant for a clear understanding of the invention, whileeliminating, for purposes of clarity, other elements that those ofordinary skill in the art will appreciate may also comprise a portion ofthe invention. However, because such elements are well known in the art,and because they do not necessarily facilitate a better understanding ofthe invention, a description of such elements is not provided herein.

Further, to the extent that the method does not rely on the particularorder of steps set forth herein, the particular order of the stepsshould not be construed as limitation on the claims. The claims directedto the method of the present invention should not be limited to theperformance of their steps in the order written, and one skilled in theart can readily appreciate that the steps may be varied and still remainwithin the spirit and scope of the present invention.

What is claimed is:
 1. A gas monitoring and control system comprising: agas sampling chamber having a chamber inlet, a chamber outlet and aninterior chamber; one or more sensors disposed within the interiorchamber, the sensors being operable to sense one or more characteristicsof a gas from a gas source and generate one or more sensor signalsrepresentative of the one or more characteristics of the gas; a samplinginlet valve in operable communication with an outlet of the gas sourceand the chamber inlet; a sampling outlet valve in operable communicationwith the chamber outlet and an inlet of the gas source, the samplinginlet valve and the sampling outlet valve operable to i) allow the gasfrom the gas source to enter the gas sampling chamber while operating ina gas sampling state, and ii) allow ambient air to enter the gassampling chamber while operating in a purge state, a pump in operablecommunication with the sampling inlet valve and the sampling outletvalve, the pump operable to i) cause the gas to flow through the gassampling chamber while operating in the gas sampling state and ii) causeambient air to flow through the gas sampling chamber while operating inthe purge state; and a controller in operable communication with the oneor more sensors, the sampling inlet valve, the sampling outlet valve andthe pump, the controller operable to cause the sampling inlet valve, thesampling outlet valve and the pump to alternate operating in the gassampling state during a sampling time period and the purge state duringa purge time period to selectively expose the one or more sensors to thegas.
 2. The gas monitoring and control system of claim 1, wherein thesampling time period is less than 2 minutes.
 3. The gas monitoring andcontrol system of claim 1, wherein a time interval between subsequentsampling time periods is greater than 1 hour.
 4. The gas monitoring andcontrol system of claim 1, wherein the sampling inlet valve and thesampling outlet valve are operable to facilitate creating a staticpressure in the gas sampling chamber while operating in a vacuumpressure state; and wherein the controller is operable to cause thesampling inlet valve and the sampling outlet valve to each operate inthe vacuum pressure state during a vacuum pressure time period.
 5. Thegas monitoring and control system of claim 1, wherein the sampling inletvalve and the sampling outlet valve are operable to isolate the gassampling chamber from the gas while operating in an isolation state; andwherein the controller is operable to cause the sampling inlet valve andthe sampling outlet valve to each operate in the isolation state duringan isolation time period.
 6. The gas monitoring and control system ofclaim 1, wherein the purge time period is less than 2 minutes.
 7. Thegas monitoring and control system of claim 1, wherein the controller isoperable to cause the sampling inlet valve, the sampling outlet valveand the pump to operate in the gas sampling state in response toreceiving a sampling command from an external computing device to samplethe gas.
 8. The gas monitoring and control system of claim 1, furthercomprising a valve actuator in operable communication with a gas sourcevalve in the gas source; and wherein the controller is in operablecommunication with the valve actuator and operable to cause the valveactuator to transition the gas source valve towards an open position ora closed position when the one or more sensor signals meets valveactuation criteria to regulate the flow of the gas in the gas source. 9.The gas monitoring and control system of claim 8, wherein the one ormore sensor signals includes a sensor signal representative of oxygenconcentration of the gas.
 10. The gas monitoring and control system ofclaim 8, wherein the one or more sensor signals meets valve actuationcriteria when the one or more sensor signals exceeds a concentrationthreshold; and wherein the controller causes the valve actuator totransition the gas source valve towards the closed position when the oneor more sensor signals exceeds the concentration threshold.
 11. The gasmonitoring and control system of claim 8, wherein the one or more sensorsignals meets valve actuation criteria when the one or more sensorsignals falls below a concentration threshold; and wherein thecontroller causes the valve actuator to transition the gas source valvetowards the open position when the one or more sensor signals fallsbelow the concentration threshold.
 12. The gas monitoring and controlsystem of claim 8, wherein the controller is operable to cause the valveactuator to transition the gas source valve towards the open position orthe closed position when a second set of one or more sensor signalssampled at a second gas source meets a second valve actuation criteria.13. The gas monitoring and control system of claim 12, wherein thesecond set of one or more sensor signals meets the second valveactuation criteria when the second set of one or more sensor signals isless than the one or more sensor signals; and wherein the controller isoperable to cause the valve actuator to transition the gas source valvetowards the open position when the second set of one or more sensorsignals is less than the one or more sensor signals.
 14. The gasmonitoring and control system of claim 12, wherein the second set of oneor more sensor signals meets the second valve actuation criteria whenthe second set of one or more sensor signals is greater than the one ormore sensor signals; and wherein the controller is operable to cause thevalve actuator to transition the gas source valve towards the closedposition when the second set of one or more sensor signals is greaterthan the one or more sensor signals.
 15. The gas monitoring and controlsystem of claim 1, where the one or more sensors includes an oxygensensor, a methane sensor, a carbon dioxide sensor, a carbon monoxidesensor, a chlorine sensor, a cyanide sensor, a hydrogen sensor, ahydrogen sulfide sensor, a nitric oxide sensor, a nitrogen sensor, asulfur oxide sensor, an overall gas composition sensor, a temperaturesensor, a pressure sensor, a humidity sensor, a flow rate sensor, a dualmethane/CO2 sensor, or combinations thereof.